Long-haul trucks, such as those manufactured by Peterbilt, Kenworth and others, have an engine compartment enclosed by a hood. The hood normally pivots forwardly from the front to provide access to the engine compartment. These hoods are generally quite heavy and require considerable effort to raise the hood manually and may inadvertently close and possibly injure the operator or mechanic. Conventional truck hoods can weigh in excess of 300 lbs.
The present approach to hood lifts is to secure the large aluminum or fiberglass hood assembly using two large line-up pins which guide the hood assembly to a closed position for travel. Security is provided simply by rubber straps, one on either side at the lower firewall position, which the driver unhooks each time engine access is required. Over time, these straps can become weak and allow the hood assembly to shake and vibrate excessively during travel particularly on rough roadway conditions.
The hood opening function requires an actuator that provides an opening of at least 225% to expose sufficient engine area to enable the operator or mechanic to perform services such as checking the oil.
Further, many operators today are women or small stature individuals who have great difficulty opening and closing the vehicle hoods of these large trucks. The hood opening procedure involves the driver having to stand on the high front bumper and grasp the hood puller on the top of the radiator cover and apply full body weight to pivot the hood forwardly. This is a strenuous and sometimes dangerous task, particularly in adverse weather conditions.
Various attempts to design suitable power-driven hood openers or assists have been made. For example, air or hydraulic systems result in a irregular opening and closing speeds even with regulators. Telescopic extension devices are inadequate as they generally do not provide enough “reach” for the open hood to a position to provide adequate access for servicing.
A shortcoming of many of these devices is that a wind or draft created by a passing motor vehicle may blow the hood shut during an inspection causing possible injury to the operator or mechanic.
U.S. Pat. No. 5,730,239 does disclose a vehicle with a torsion bar hood assist. The torsion bar hood lift includes a torsion bar mounted with the free end positioned to engage and travel along a hood interior surface as the hood of the vehicle is opened and closed. As the hood is closed, the torsion bar bends to twist to store energy which is then transferred to the hood to assist in hood opening when the hood is lifted. The free end of the torsion bar supports a hood engagement member, such as a roller, to reduce friction between the torsion bar and the hood as the energy is transferred. The torsion bar is typically supported at two locations with a bearing block being used to further reduce friction. The free end of the torsion bar engages a hood reinforcing member or plate which may comprise a hood mounting bracket and travels against this plate during hood opening and closing.
Notwithstanding efforts in the prior art to provide various mechanical and electrical hood lift assists, such as that shown in the '239 patent, there nevertheless exists a need for an actuator which will provide an opening at least twice its original retracted length so it is functionally efficient to open the hood of trucks with the longest hood.